Semiconductor devices have been more highly integrated in order to provide high performance and low cost thereof. In particular, the integration density of semiconductor devices directly influences the costs of the semiconductor devices. The integration degree of a conventional two-dimensional (2D) memory device is mainly determined by an area that a unit memory cell occupies. Therefore, the integration density of the conventional 2D memory device is greatly affected by the level of a technique for forming fine patterns.
Three-dimensional (3D) semiconductor devices including three-dimensionally arranged memory cells address the above limitations of two-dimensional memory devices. Manufacturing techniques and products that are capable of reducing bit cost and realizing reliable products are desired for successful mass production of the 3D semiconductor devices.